Increased risk of cancer among 3663 patients with cutaneous lupus erythematosus: a Swedish nationwide cohort study

Background Other autoimmune diseases have been associated with higher risks for cancer, and numerous case reports of cutaneous lupus erythematosus (CLE) and different cancer types are available. Objectives To estimate the overall and specific cancer risks in a nationwide cohort study of patients diagnosed with CLE in Sweden and compare that risk with that in a control cohort without CLE. Methods A cohort of 3663 individuals with CLE and a matched control cohort from the general population (three controls to each CLE case) without a diagnosis of CLE were derived from the Swedish National Patient Register, 1997-2007, and were electronically linked to the Swedish Cancer Register and the Swedish Cause of Death Register. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to compare the observed vs. the expected numbers of cancers. Results A total of 183 incident cancers occurred within the observation interval, yielding a HR of 1.8 (95% CI 1.5-2.2) for cancer overall. Median follow-up was 4.1 years. About a fourfold risk increase was seen for buccal cancer, lymphomas, respiratory cancer and nonmelanoma skin cancer. Conclusions Patients with CLE appear to have an elevated risk for certain cancer types, an increase that remains when excluding patients also diagnosed with systemic lupus erythematosus. Our findings point to the importance of counselling about not smoking and sun avoidance, and underscore the need for specialized monitoring of this patient group along with bench-to-bedside research efforts to clarify pathogenesis.